MEASUREMENT OF THE LIPOPHORIN TITER IN THE LARVAL HEMOLYMPH OF THE SOUTHWESTERN CORN-BORER, DIATRAEA-GRANDIOSELLA, BY ELISA

An enzyme-linked immunosorbent assay (ELISA) was developed to measure the lipophorin titer in the hemolymph of the southwestern corn borer, Diatraea grandiosella. Results obtained using indirect and direct ELIS A methods were compared. The indirect ELISA was then used to compare t he lipophorin titers in the hemolymph of non-diapause, pre-diapause, a nd diapause larvae. The mean lipophorin titer in the hemolymph of non- diapause larvae was 2.5 mg/ml in fourth instar larvae and increased to 3.9 mg/ml during the fifth and sixth instars. The mean lipophorin tit er in the hemolymph of pre-diapause larvae was 2.3 mg/ml in 13 day old larvae and increased to 4.0 mg/ml in 22 day old larvae. The mean tite r then decreased significantly until day 40, but increased to 5.1 mg/m l in 49 day old larvae after they had entered diapause and held at c. 3 mg/ml until larvae were about 70 days old, when it increased to c. 5 mg/ml and remained constant for at least the next 20 days. The amount of lipid in the hemolymph was also measured and correlated to the amo unt of lipophorin present.